Reader fixes after fuzz testing runs

Signed-off-by: James Hamlin <jfhamlin@gmail.com>

Author: jfhamlin

pkg/lang/set.go

@@ -25,18 +25,26 @@ func CreatePersistentTreeSetWithComparator(comparator IFn, keys ISeq) interface{
 }
 
 func NewSet(vals ...interface{}) *Set {
+	set, err := NewSet2(vals...)
+	if err != nil {
+		panic(err)
+	}
+	return set
+}
+
+func NewSet2(vals ...interface{}) (*Set, error) {
 	// check for duplicates
 	for i := 0; i < len(vals); i++ {
 		for j := i + 1; j < len(vals); j++ {
 			if Equiv(vals[i], vals[j]) {
-				panic(NewIllegalArgumentError(fmt.Sprintf("duplicate key: %v", vals[i])))
+				return nil, NewIllegalArgumentError(fmt.Sprintf("duplicate key: %v", vals[i]))
 			}
 		}
 	}
 
 	return &Set{
 		vals: vals,
-	}
+	}, nil
 }
 
 var (

pkg/lang/symbol.go

@@ -2,6 +2,7 @@ package lang
 
 import (
 	"fmt"
+	"regexp"
 	"strings"
 )
 
@@ -11,6 +12,10 @@ type Symbol struct {
 	name string
 }
 
+var (
+	symbolRegex = regexp.MustCompile(`^(?:[^0-9/].*/)?(?:/|[^0-9/][^/]*)$`)
+)
+
 // NewSymbol creates a new symbol.
 func NewSymbol(s string) *Symbol {
 	ns, name := "", s
@@ -83,6 +88,9 @@ func isValidSymbol(ns, name string) bool {
 	} else {
 		full = ns + "/" + name
 	}
+	if !symbolRegex.MatchString(full) {
+		return false
+	}
 
 	// early special case for the division operator /
 	if full == "/" {
@@ -97,11 +105,11 @@ func isValidSymbol(ns, name string) bool {
 		// empty namespace
 		return false
 	}
-	if strings.HasSuffix(name, ":") {
+	if strings.HasSuffix(name, ":") || strings.HasSuffix(ns, ":") {
 		// name ends with a colon (match clojure)
 		return false
 	}
-	if strings.Contains(name, "::") {
+	if strings.Contains(full, "::") {
 		// name contains double colon
 		//
 		// NB: clojure reader rejects this, but clojure.core/symbol

pkg/reader/reader.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"math/big"
 	"regexp"
 	"strconv"
 	"strings"
@@ -191,6 +192,12 @@ type (
 		posStack []pos
 
 		pendingForms []any
+
+		// nested syntax quoting grows forms exponentially, so we
+		// limit the depth to prevent DoS.
+		//
+		// Found by the fuzz tester.
+		syntaxQuoteNestCounter int
 	}
 )
 
@@ -512,7 +519,11 @@ func (r *Reader) readSet() (interface{}, error) {
 	if err != nil {
 		return nil, err
 	}
-	return lang.NewSet(vals...), nil
+	set, err := lang.NewSet2(vals...)
+	if err != nil {
+		return nil, r.error("invalid set: %w", err)
+	}
+	return set, nil
 }
 
 func (r *Reader) readString() (interface{}, error) {
@@ -724,6 +735,14 @@ func (r *Reader) readQuote() (interface{}, error) {
 }
 
 func (r *Reader) readSyntaxQuote() (interface{}, error) {
+	if r.syntaxQuoteNestCounter > 10 {
+		return nil, r.error("syntax-quote nesting too deep")
+	}
+	r.syntaxQuoteNestCounter++
+	defer func() {
+		r.syntaxQuoteNestCounter--
+	}()
+
 	node, err := r.readExpr(false, 0)
 	if err != nil {
 		return nil, err
@@ -1114,6 +1133,12 @@ func (r *Reader) readNumber(numStr string) (interface{}, error) {
 		if err != nil {
 			return nil, r.error("invalid ratio: %s", numStr)
 		}
+
+		// if denom is 0, error
+		if denomBig.ToBigInteger().Cmp(big.NewInt(0)) == 0 {
+			return nil, r.error("divide by zero")
+		}
+
 		return lang.NewRatioBigInt(numBig, denomBig), nil
 	}
 
@@ -1291,6 +1316,14 @@ func (r *Reader) readConditional(eofOK bool, stopRune rune) (any, error) {
 			return nil, r.error("splicing read-cond form must be seqable")
 		}
 		seq := seqable.Seq()
+		if seq == nil {
+			// return the next expression (not nil!)
+			form, err := r.readExpr(eofOK, stopRune)
+			if err != nil {
+				return nil, err
+			}
+			return form, nil
+		}
 		first := seq.First()
 		for seq = seq.Next(); seq != nil; seq = seq.Next() {
 			r.pendingForms = append(r.pendingForms, seq.First())

pkg/reader/testdata/fuzz/FuzzRead/212816a63358983b

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("#{0 0}")

pkg/reader/testdata/fuzz/FuzzRead/48c07ddc40007f0b

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("0/0")

pkg/reader/testdata/fuzz/FuzzRead/7dac166db0afb1bc

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("##```````````````````````s#")

pkg/reader/testdata/fuzz/FuzzRead/b27cc02acdd412b9

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("0#?@(:glj()0)")

pkg/reader/testdata/fuzz/FuzzRead/f21bc1b3b9bfb37d

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("`A:/0")